Myagmarsuren Baldan,1– 3 Shuang Zhang,1– 3 Qi Sun,1– 3 Yan Su,3,4 Dong Mei,3,5 Ran Sun,1– 3 Ao Zheng,1– 3 Danni Liu,1– 3 Jie Zhang,1– 3 Ran Huo,1– 3 Yang Tian,1– 3 Le Han,1– 3 Shibo Wang,1– 3 Yaoqi Wang,1– 3 Chunying Cui1– 3 

1School of Pharmaceutical Sciences, Capital Medical University, Beijing, People’s Republic of China; 2Beijing Area Major Laboratory of Peptide and Small Molecular Drugs, Beijing Laboratory of Biomedical Materials, Engineering Research Center of Endogenous Prophylactic of Ministry of Education of China, Beijing, People’s Republic of China; 3Laboratory for Clinical Medicine, Capital Medical University, Beijing, People’s Republic of China; 4Medical Oncology Department, Pediatric Oncology Center, Beijing Children’s Hospital, Capital Medical University, National Center for Children’s Health, Beijing, People’s Republic of China; 5Department of Pharmacy, Beijing Children’s Hospital, Capital Medical University, National Center for Children’s Health, Beijing, People’s Republic of China

Correspondence: Chunying Cui, Department of Pharmaceutics, School of Pharmaceutical Sciences, Capital Medical University, No. 10 Youanmenwai Street, Fengtai, Beijing, 100069, People’s Republic of China, Tel +86-10-8391-1668, Email ccy@ccmu.edu.cn Yaoqi Wang, Department of Pharmaceutics, School of Pharmaceutical Sciences, Capital Medical University, No. 10 Youanmenwai Street, Fengtai, Beijing, 100069, People’s Republic of China, +86-10-8391-1673, Email wangyaoqi@ccmu.edu.cn

Background: Resistance to traditional treatments has spurred research into innovative therapeutic approaches for tumors. Among these innovative treatments, photothermal therapy (PTT) has gained increasing attention for its use of photothermal agents (PTAs) to convert light into heat for localized tumor ablation. However, PTT faces limitations due to heat shock protein 70 (HSP70)-mediated resistance in tumor cells. Combining PTT via indocyanine green (ICG) with siRNA HSP70 could reduce the thermal resistance of the tumor, thereby enhancing treatment efficacy. Albumin-based nanoparticles (NPs) can effectively deliver ICG and siRNA into tumor cells. When exposed to near-infrared (NIR) light, these nanoparticles trigger lysosomal escape and release, further enhancing gene silencing activity.
Methods: This study aimed to develop a biocompatible delivery system, HSA@ICG/siRNA NPs, for photothermal-enhanced tumor therapy. The nanoparticles were characterized for size, charge, surface functionalization, and photoconversion properties. In vitro antitumor efficacy was evaluated using MTT assay, calcein AM/PI staining, RT-PCR, and Western blot in 4T1 tumor cells. In vivo, we assessed photothermal effects, biodistribution, tumor inhibition, and biosafety following irradiation.
Results: Characterization confirmed the successful synthesis of uniform, stable HSA@ICG/siRNA NPs with effective photothermal conversion properties. Cellular uptake studies revealed high siRNA internalization, with laser-induced lysosomal escape enhancing cytoplasmic delivery. In vitro, gene silencing reduced mRNA and protein levels by 82.8% and 65%, respectively. In vivo, local tumor temperature increased to 42°C within 3 minutes, indicating a mild but effective photothermal effect. Tumor inhibition rates were 50.00% ± 9.16% for HSA@ICG and 71.26% ± 7.92% for HSA@ICG/siRNA, demonstrating enhanced tumor suppression. The treatment achieved sustained tumor targeting with minimal off-target toxicity.
Conclusion: As a dual-function photothermal therapy agent, HSA@ICG/siRNA NPs combine targeted gene silencing with photothermal effects, demonstrating significant therapeutic promise. This integrated approach addresses tumor resistance, offering a potential advancement in cancer treatment strategies.

Keywords: photothermal therapy, human serum albumin, HSP70 siRNA, lysosome escape, gene silencing